Background
[0001] Wellhead seals are used to seal across the annular space between the exterior of
a hanger and the interior of a wellhead housing in which the hanger is supported.
Many types of seals have been used in the past. Such seals have included resilient
annular members which are positioned within the annular space and compressed axially
to expand them into sealing engagement with the surfaces defining the interior and
exterior of the annular space, such as disclosed in U. S. Patent No. 3,797,864.
[0002] Other seals include metal members having lips urged into engagement with the inner
and outer sealing surfaces as shown in U. S. Patent Nos. 2,405,152; 2,746,486; 4,131,287;
and 4,178,020.
[0003] Some seals have utilized a combination of resilient and metal seals such as illustrated
by U. S. Patent Nos. 4,488,740 and 4,550,782.
[0004] Additionally seals have been provided which utilize a resilient or metal seal which
is mechanically wedged or cammed into sealing engagement with the walls of the annular
space in a well bore. Other seal structures have included threaded or roughened sealing
surfaces, such as wickers, which provide a positive metal-to-metal seal. U. S. Patent
No. 4,595,053 is an example of these two types of seals.
Summary
[0005] The present invention provides an improved wellhead seal for sealing across the annular
space between the exterior of a hanger and the interior of a wellhead housing having
a seal ring with upper and lower rims, the lower rim having resilient metal lips for
engaging the exterior of the hanger and the upper rim having external gripping and
sealing teeth or serrations and an actuating ring whereby downward movement of the
actuating ring moves the upper rim outward to force its gripping and sealing teeth
into tight sealing engagement with the interior of the wellhead housing.
[0006] An object of the present invention is to provide an improved annular wellhead seal
for sealing across the annular space between two tubular well members which ensures
tight sealing engagement with its sealing surfaces.
[0007] Another object is to provide an improved annular wellhead seal with improved metal-to-metal
seals against both the interior and exterior of the annulus.
[0008] A further object is to provide an improved annular wellhead seal in which the interior
and exterior seals are of different types and function independently of each other.
[0009] Still another object is to provide an improved annular wellhead metal seal which
will tolerate vertical and radial movement between the members which are to be sealed
with respect to one another.
[0010] A still further object is to provide an improved annular wellhead metal seal which
will support axial forces imposed by the subsequent casing and testing loads developed
from subsequently set hangers.
Brief Description of the Drawings
[0011] These and other objects and advantages of the present invention are hereinafter set
forth and explained with reference to the drawings wherein:
FIGURE 1 is a partial sectional view of the improved annular wellhead seal as it is
being run into a wellhead for subsequent landing within the annular space across which
it is to seal.
FIGURE 2 is another partial sectional view of the improved wellhead seal after it
has been landed and prior to energization.
FIGURE 3 is another partial sectional view of the improved wellhead seal after it
has been moved into tight sealing engagement across the annular space.
FIGURE 4 is a partial sectional view of a modified form of the improved annular wellhead
seal of the present invention.
FIGURE 5 is a partial sectional view of a modified form of the improved annular wellhead
seal.
Description of the Preferred Embodiment
[0012] Improved seal assembly 10 of the present invention is shown in its running position
in FIGURE 1. Seal assembly 10 includes seal ring 12 and actuating ring 14. As shown
in FIGURE 1, seal assembly 10 is positioned within wellhead member 16 and is being
lowered therein on a suitable running tool (not shown). Seal ring 12 includes annular
body 18 having lower rim 20 extending downward from the inner portion of body 18 and
upper rim 22 extending upward from the outer portion of body 18. Wiper 24 is positioned
within groove 26 around the exterior of body 18 and is sufficiently large to engage
the interior of wellhead member 16 as seal assembly 10 is being lowered therein.
[0013] Lower rim 20 includes groove 28 on the lower portion of its interior surface with
wiper 30 being positioned therein and being sufficiently large to wipe the outer sealing
surface of the hanger against which seal assembly 10 is to seal. Spaced above groove
28 is seal area 32 having sealing lips 34 and 36. Both of lips 34 and 36 extend inwardly
with upper lip 34 extending upwardly and inwardly and lower lip 36 extending downwardly
and inwardly. The outer diameter of lips 34 and 36 is sufficiently small to ensure
proper sealing against the exterior of the hanger against which seal assembly 10 is
to seal. Upper rim 22 includes external teeth or gripping and sealing elements or
serrations 38 and internal multiple upward facing camming surfaces 40. Serrations
38 are intended to include small parallel grooves with pointed projections between
the grooves. The inner edges of camming surfaces 40 terminate at flat cylindrical
surfaces 40a and the outer edges of camming surfaces 40 terminate at flat cylindrical
surfaces 40b so that camming surfaces 40 and cylindrical surfaces 40a and 40b form
a toothed profile 40c with recesses 40d. Upper rim 22 extending upwardly from the
outer portion of annular body 18 provides shoulder 42 on the upper part of body 18
within rim 22.
[0014] Actuating ring 14 is annular in shape and includes inner tapered landing seat 44
on which a subsequent well member could be landed, external multiple downward facing
camming surfaces 46 which mate with the camming surfaces 40 on the interior of upper
rim 22. The outer edges of camming surfaces 46 terminate at flat cylindrical surfaces
46a and the inner edges of camming surfaces 46 terminate at flat cylindrical surfaces
46b so that camming surfaces 46 and cylindrical surfaces 46a and 46b form a toothed
profile 46c with recesses 46d. In running position, actuating ring 14 is in its upper
position, as shown in FIGURE 1, and in such position its lower surface 48 is spaced
above shoulder 42 on body 18 and camming surfaces 40 and 46 are in contact. Toothed
profiles 40c of upper rim 22 are located in recesses 46d of actuating ring 14 and
toothed profiles 46c of actuating ring 14 are located in recesses 40d of upper rim
22 so that toothed profiles 40c and 46c are interlocked. This spacing between surfaces
42 and 48 should be sufficient to allow full travel of actuating ring 14 in its downward
setting movement as hereinafter described. Actuating ring 14 includes an outwardly
extending flange 50 at its upper end above surfaces 46 and the lower surface of flange
50 is also spaced above the upper end of upper rim 22 by a sufficient distance to
allow full setting movement of actuating ring 14. Actuating ring 14 also includes
preparation for receiving the suitable running tool (not shown).
[0015] As shown in FIGURE 2, sealing assembly 10 is landed in annular space 52 between the
interior of wellhead member 16 and the exterior of hanger 54 above upwardly facing
shoulder 56 of hanger 54. Hanger 54 is landed upon in wellhead member 16 with downwardly
facing shoulder 57 of hanger 54 being in supporting contact with upwardly facing shoulder
58 of wellhead member 16 and includes the usual mud slots 55 which allow circulation
of cement or other well fluids prior to the landing of seal assembly 10 in annular
space 52. With seal assembly 10 landed in annular space 52 as shown in FIGURE 2 the
lower end of lower rim 20 is in engagement with shoulder 56 on hanger 54. In this
position, wiper 30 in its downward movement has wiped external sealing surface 60
of hanger 54 free of trash, mud and all other materials which would interfere with
proper sealing of lips 34 and 36 against sealing surface 60. Also, wiper 24 has wiped
interior sealing surface 62 of wellhead member or housing 16 free of trash, mud and
all other materials which would interfere with proper sealing of gripping teeth 38
to sealing surface 62.
[0016] With seal assembly 10 in the position shown in FIGURE 2, it is ready for the engagement
of gripping teeth 38 of upper rim 22 with sealing surface 62 of wellhead member 16.
Actuating ring 14 is moved downward by a suitable tool (not shown) so that its exterior
camming surfaces 46 move downward on camming surfaces 40 of upper rim 22 to wedge
gripping teeth 38 into tight gripping and sealing engagement with sealing surface
62. In this position as shown in FIGURE 3, actuating ring 14 has moved to its lower
position with its lower surface 48 engaging shoulder 42 on the upper portion of seal
body 18 and also with the lower surface of flange 50 in engagement with the upper
surface of rim 22. These two engagements between actuating ring 14 and seal ring 12
provide suitable stops for the downward movement of actuating ring 14 at a position
when maximun force has been exerted on upper rim 22 to ensure positive deformation
of sealing surface 62 by gripping teeth 38. Also, lower inner surface 49 of actuator
14 engages upper surface 54a of hanger 54. These engagements provide a transfer of
the load of a hanger which is subsequently landed on landing seat 44. This load is
then transferred through actuating ring 14 and rim 22 into housing 16, through actuating
ring 14, shoulders 42 and 48, hanger 54 and seat 58 into housing 16 and through actuating
ring 14, shoulder 54a and seat 58 into housing 16. Cylindrical surfaces 46a of actuating
ring 14 have also been moved downward to become in tight contact with cylindrical
surfaces 40b of upper rim 22 and thereby eliminate any tendency of actuating ring
14 to move upward in relation to seal ring 12. Also, sealing by lips 34 and 36 against
sealing surface 60 is complete and is enhanced by the configuration of the lips. Fluid
pressure from the interior of hanger 54 acts on exterior surface 34a of upper lip
34 to urge lip 34 into tight sealing engagement with surface 60 of hanger 54. In a
similar manner fluid pressure from the exterior of hanger 54 acts on exterior surface
36a of lower lip 36 to urge lip 36 into tight engagement with surface 60 of hanger
54. Such pressure urging of lips 34 and 36 towards surface 60 increases as the pressure
increases. As can be seen in FIGURE 1, lips 34 and 36 protrude inward from surface
20 and as such are able to compensate for eccentricity between wellhead member 16
and hanger 54 and still sealingly engage surface 60.
[0017] It should be noted that the exterior surface 61 of lower rim 20 is spaced substantially
from the interior surface 62 of wellhead housing 16. This provides a space for the
trash and mud which is wiped from surface 62 by wiper 24 so that such trash and mud
cannot interfere with the sealing operations of seal assembly 10.
[0018] Sealing assembly 10 is retrievable from its sealing position in annular space 52
by lifting actuating ring 14 with a suitable well tool (not shown) which can engage
lower surface 48 which is spaced from the upper end of hanger 54 or running tool preparation.
Lifting of actuating ring 14 moves its camming surfaces 46 upwardly to release the
force exterted on upper rim 22. When actuating ring 14 reaches its upper position
as shown in FIGURES 1 and 2, the toothed profiles on actuating ring 14 and upper rim
22 again become interlocked to transmit the lifting force to seal ring 12. This upward
force is sufficient to cause a release of the gripping engagement of gripping teeth
38 with sealing surface 62 to allow completion of the retrieval of seal assembly 10.
[0019] Sometimes well debris, such as gravel or clay, becomes deposited on upwardly facing
shoulder 58 of wellhead member 16 and prevents downwardly facing shoulder 57 of hanger
54 from contacting shoulder 58. Pressure subsequently present in the interior of hanger
54 may crush the debris and cause hanger 54 to move downward relative to wellhead
member 16 and sealing assembly 10. Since sealing lips 34 and 36 are not firmly locked
to hanger seal surface 60, such relative vertical movement between the sealing lips
and surface 60 does not compromise the sealing engagement of the lips 34 and 36.
[0020] It should be recognized in the preferred embodiment of FIGURES l, 2 and 3 that the
Brinell hardness of seal assembly 10 in the area of serrations 38 is preferably greater
than the Brinell hardness of surface 62 of wellhead member 16 so that serrations
38 will bite into surface 62 when actuating ring 14 is moved downward. In some situations
it may be preferable to place serrations at the appropriate location on surface 62
rather than on seal assembly 10. In such a situation it would be preferable to have
the serration area of the wellhead member a higher Brinell hardness than the smooth
exterior surface of the seal assembly.
[0021] Annular wellhead seal assembly 64 shown in FIGURE 4 is a modified form of the improved
seal of the present invention. Seal assembly 64 is provided to seal between wellhead
housing 66 and hanger 68 which has been landed therein. Hanger 68 includes body 70
with upstanding rim 72, the outer surface 74 of rim 72 being spaced inward from inner
surface 76 of housing 66. The inner surface 78 of rim 72 includes multiple upward
facing camming surfaces 80 and outer surface 74 includes serrations 81. Inner surface
76 of housing 66 has a plurality of serrations 82 therein as shown. Seal ring 84
is positioned within annulus 88 between inner surface 76 of housing 66 and outer surface
74 of rim 72 and has its lower end in engagement with upwardly facing shoulder 86
of hanger 68 at the lower end of annulus 88. Seal assemby 64 includes seal ring 84
and actuating ring 90 which coact together with rim 72 to complete the sealing across
annulus 88. Actuating ring 90 includes multiple downward facing camming surfaces 92
which mate and coact with camming surfaces 80 as previously described with respect
to seal assembly 10.
[0022] Seal assembly 64 is shown in FIGURE 4 in its set position with actuating ring 90
moved downward to engage interior shoulder 94 on hanger 68 within rim 72. With actuating
ring 90 in this position the camming action has been completed and the actuating ring
90 and rim 72 have their outer and inner cylindrical surfaces in engagement to retain
rim 72 in its position of gripping engagement of its serrations 81 with the interior
surface of seal ring 84 and also forcing seal ring 84 outwardly so that its exterior
surface is in tight gripping and sealing engagement with serrations 82 on interior
surface 76 of housing 66. Actuating ring 90 includes flat upper surface 96 against
which a suitable setting tool may exert a downward load to move actuating ring 90
downward into set position. Tapered surface 98 extends downward and inward from the
inner portion of flat surface 96 and can be used as a landing seat for well structures
which are to be subsequently landed within housing 66. If retrieval of actuating
ring 90 is desired, a suitable interior profile for engagement by a retrieval tool
would be provided on the interior of actuating ring 90. Also, groove 100 on the upper
interior of seal ring 84 could be engaged by a suitable retrieval tool for the retrieval
of seal ring 84 after actuating ring 96 has been raised above groove 100.
[0023] It should be noted that in most wellhead sealing situations, the condition of the
sealing surface on the exterior of the hanger is known to be satisfactory while the
condition of the sealing surface of the interior of the wellhead housing is unpredictable.
The present invention provides an improved metal-to-metal seal against both such surfaces.
[0024] Another modified form of the present invention is shown in FIGURE 5 wherein seal
assembly 110 is energized by exterior tapered surface 146 of actuating ring 114 engaging
interior tapered surface 140 of upper rim 122 to urge upper rim 122 into sealing engagement
with the interior surface of wellhead member 116. Shear pin 123 is inserted in hole
125 through rim 122 and into energizing ring 114 to retain seal assembly 110 in an
unenergized position until shoulder 57 engages upwardly facing shoulder 56 of wellhead
member 116.
1. An annular wellhead seal comprising a seal ring having a central body with an upper
outer rim extending above the central body and a lower rim extending below the central
body, said upper rim having external gripping surface and an internal camming surface,
said lower rim having sealing means on its inner surface to provide a metal-to-metal
sealing, and an actuating ring positioned within said upper rim and having an external
camming surface mating with the camming surface on the interior of said upper rim
whereby movement of said actuating ring forces said upper rim outwardly to cause said
external gripping surface to engage an inner sealing surface in tight gripping and
sealing engagement.
2. An annular wellhead seal according to claim 1 including a wiper carried by said
seal ring on its exterior below said upper rim for wiping trash, mud and other materials
from the sealing surface against which said upper rim external gripping surface is
to seal.
3. An annular wellhead seal according to claim 1 including a wiper carried by said
lower rim below its sealing means for wiping trash, mud and other materials from the
sealing surface against which said lower rim sealing means is to seal.
4. An annular wellhead seal according to claim 1 wherein said sealing means on said
lower rim include an upper metal sealing lip facing upwardly and inwardly, and a lower
metal sealing lip facing downwardly and inwardly.
5. An annular wellhead seal according to claim 1 including means limiting the travel
of said actuating ring when it has reached the end of the camming surfaces.
6. An annular wellhead seal according to claim 1 wherein said camming surfaces on
said upper rim and said actuating ring include multiple mating camming surfaces.
7. An annular wellhead seal according to claim 6 including annular shoulders on said
upper rim and said actuating ring between individual cam surfaces providing means
for urging said seal ring inward to release when said actuating ring is in its released
or unset position.
8. An annular wellhead seal comprising a hanger having an upstanding rim with internal
multiple camming surfaces and external serrations, seal means positioned in surrounding
relationship to the exterior surface of said hanger rim, cam means coacting with said
rim to wedge said rim outwardly to provide sealing engagement with the interior surface
of the wellhead annulus and sealing engagement with the exterior surface of said rim,
said cam means including a cam ring having multiple camming exterior surfaces mating
with said rim camming surfaces whereby forcing said cam ring downward with respect
to said rim, cams said rim outwardly to provide a tight gripping and sealing engagement
between said seal means and the annulus interior wall and between said seal means
and the exterior surface of said rim.
9. An annular wellhead seal according to claim 8 wherein said means includes a seal
ring, said rim having mating multiple camming interior surfaces mating with said cam
ring camming surfaces and coacting to set said seal ring.
10. An annular wellhead seal according to claim 8 including said seal means includes
serrations on one surface of each of the surfaces which are in gripping and sealing
engagement with each other.
11. An annular wellhead seal according to claim 9 including a wellhead housing having
an interior sealing surface with serrations therein, and serrations on the exterior
surface of said rim whereby the forcing of said seal ring against said serrations
provides such tight gripping and sealing engagement.
12. An annular wellhead seal comprising sealing means adapted to have at least one
of its surfaces in tight gripping and sealing engagement with a surface facing the
sealing means, cam means for wedging said sealing means into tight gripping and sealing
engagement with the surface facing the sealing means, said cam means including a cam
ring having multiple camming surfaces so that the downward movement of the cam ring
urges said sealing means into its tight gripping and sealing engagement.
13. An annular wellhead seal according to claim 12 including a hanger having an upstanding
rim forming said sealing means, the inner surface of said rim having mating multiple
camming surfaces to said cam means.
14. An annular wellhead seal according to claim 12 including a hanger having an upstanding
rim, said rim having mating multiple camming surfaces to said cam means, and said
seal means is a seal ring surrounding the exterior of said rim.
15. An annular wellhead seal according to claim 14 wherein said rim includes serrations
on its exterior surface.